A. Field of the Invention
The present invention relates to a device for obtaining a new type of novelty yarn and the yarns thus obtained.
The invention relates more particularly to an improved device for obtaining, from at least two yarns, both novelty yarns presenting localized effects such as flames and buttons, loops, and novelty yarns presenting effects of color and/or yarns in which one of the two constituents forms a core covered entirely by the other constituent.
B. Description of the Prior Art
Numerous techniques have been proposed for making novelty yarns. Concerning those presenting localized effects over their length (i.e. flames, buttons and loops), the most wide-spread technique consists in winding at least one effect yarn about a core yarn, for example by using a twister comprising a plurality of pairs of delivery rolls or an uptwister with hollow spindle possibly equipped with a false twist means. By varying the flowrate of the effect yarn with respect to the core yarn and/or the speed of wind and/or by using a wrapping needle, it is possible to obtain a large variety of novelty yarns. However, this technique presents numerous drawbacks, the major ones being, on the one hand, a low speed of production and, on the other hand, the necessity of using an additional bonding yarn in order to stabilize the effects.
To increase the speeds of production, it has been proposed to assemble core and effect yarns by false twist, possibly subjecting them to a heat treatment before and/or after passage in the false twist member. With this technique, it is desired to obtain stable effects which do not slide on the core yarn, it is also necessary to use a bonding yarn.
Apart from the novelty yarns which present localized effects, it has also been proposed to make so-called core spun yarns in which one of the constituents, generally constituted by a multi-filament yarn, is entirely covered over the whole of its periphery by a second constituent generally constituted by discontinuous fibers. In the following description, this type of yarn will also be designated by the term novelty yarns. Such core-spun novelty yarns are generally obtained on ring spinning frames, the core being introduced in the rove of fibers upstream of the last pair of rolls of the train drafting the fibrous rove. According to this technique, the speed of production is also low and in particular, the range of yarns which may be made is limited.
Finally, it has been envisaged, in No. FR-A-2 426 102, to make novelty yarns comprising a core yarn and an effect yarn in which the effect yarn is attached to the core spun yarn by chain stitches formed by the core spun yarn itself. According to this document, although it is not clear from the description, the technique used to make such a yarn requires the use of a warp knitting machine comprising at least two guide bars, one of the bars forming chain stitches and the other working in weft so as to form the effects. The weave of the two bars may possibly be reversed so that the two yarns alternately form chain stitches and wefts.
In such a type of spun yarn, the effects are bonded well by the chain stitches, but it should be noted that it requires the use of expensive equipment which is delicate to operate and which lacks versatility. Moreover, winding of the yarns formed involves either the transformation of this loom to wind each of the yarns individually, or, if the yarns are wound on a common support tube, a complementary operation to place them on the individual supports.
Other solutions employing knitting machines or the like have been proposed for making the yarns, as disclosed in No. CH-A-592 765, No. GB-A-1 488 458 and No. FR-A-2 329 779. These solutions, like those forming the subject matter of No. FR-A-2 426 102 mentioned above, lack versatility and generally enable only one type of yarn to be obtained.